1. Field
The present invention relates to an iodine (I2) or bromine (Br2) adsorbent including a zeolite having a Si/Al ratio of 15 or greater; an I2 or Br2 carrier including the I2 or Br2 adsorbent; a column filled with the I2 or Br2 adsorbent; a article composed of the I2 or Br2 adsorbent or having the I2 or Br2 adsorbent attached thereto; a method for adsorbing or removing I2 or Br2 using the I2 or Br2 adsorbent; an iodine- or bromine-containing zeolite composite including a porous zeolite and iodine (I2) or bromine (Br2) confined in the pores of the zeolite; a semiconductor material including the iodine- or bromine-containing zeolite composite; and a method for preparing an iodine- or bromine-containing product using the iodine- or bromine-containing zeolite composite.
2. Description of the Related Art
Iodine is a volatile (sublimating), corrosive solid at room temperature. Because of its volatility, it is difficult to accurately weigh the amount of iodine on a scale, and iodine vapor can corrode the scale being used. Likewise, bromine, being a highly volatile and corrosive liquid at room temperature, is difficult to accurately weigh on a scale, and bromine vapor can corrode the scale being used.
Of the 37 known isotopes of iodine, all are radioactive elements except the stable I-127. Whereas most of the radioactive isotopes have very short half-lives of 1 day or shorter, I-124, I-125, I-126, and I-131 have relatively long half-lives of 4-60 days. Among them, I-131 results in the greatest radioactive damage in the event of atomic reactor explosion. I-129 decays over a very long period of time with a half-life of Ser. No. 15/700,000 years. Due to its slow radioactive radiation, it is less dangerous than other radioactive isotopes and is classified as a potential radioactive material since a large amount of radioisotopes, despite slow radioactive radiation, can lead to high radiation doses. However, the capture of this isotope is an important part in the process of nuclear waste because about 0.55% of uranium decays into I-129. Since I-129 exists naturally at a certain level, it can be used as an index for chronometry. That is to say, the trace amount of the naturally existing I-129 captured enables accurate timekeeping.
In solutions, iodine usually exists as iodide ions (I−) and iodine molecules (I2). Theoretically, the iodide anions can be recovered using an anion exchanger. However, once the ions flow into seawater, it is impossible to recover the iodide ions using the anion exchanger because of the high chloride concentration in seawater. The neutral iodine molecules are oxidative and are easily converted into iodide ions via oxidation by various reducing materials present in seawater. Therefore, the neutral iodine molecules need to be recovered from the hydrosphere including the sea or air before they are converted into iodide ions. For this reason, a method allowing for effective capturing of iodine included in water or air may be useful for blocking the propagation of the radioactive iodine.
Until recently, activated carbon or zeolite has been used to recover neutral iodine molecules from water or air. However, these adsorbents tend to reduce a significant amount of the adsorbed neutral iodine to iodide ions. Due to this property, it is difficult to remove iodine, particularly that in water. Therefore, it is necessary to develop an iodine adsorbent or capturing agent capable of capturing neutral iodine well without converting the neutral iodine molecules to iodide ions.